Means for controlling the supply of air to the closed cabins of aircraft



Ap l 3,194 S.GRUNERTEI'AL 12,316,237

MEANS FOR CONTROLLING THE SUPPLY OF AIR I TO THE CLOSED CABINS OF AIRCRAFT Filed-Jan. 4, 1941 2 Sheets-Sheet l R 1 five/7 for: IS/56FR/E0 aid/manna /fbc/r'flfforneJ s' pri '13 1943. s. GR UNERT ET AL I z'316237 MEANS FOR CONTROLLING THE SUPPLY OF AIR TO THE CLOSED CABINS OF AIRCRAFT v Filed Jan. 4, 1941 2 Sheets-Sheet 2 m- /m ehforf ,S/EGFfi/ED 6 0 u'warr m/ r hh/YS b5 6 r/wir Amraeys' Patented Apr. 13, 1943] 2,316,237 MEANS FOR CONTROLLING 'rna SUPPLY or AIR TO THE CLO CRAFT.j

SED CABINS 1 OF AIR- Siegfried Griinert; Ka ehameha Hans Ide, Berlin-Grunau, Germany: vested in the Alien Property Custodian 1 P application January 4, 1941, Serial No. 373,190 h In Germany November 25, 1939 scams. (0!. 128-2054) The inventionrelates to novel and improved means for controlling the supply of air to the closed cabin of an aircraft. 3 i An objectof the invention is-the maintenance.

of aconstant amount of air at'any altitude of the aircraft, this amountof air being blown into the cabin as fresh. air by means oi a compressor.

A further object is to provide novel means for either heating or coolingthe air fedinto the cabin.

Further objects or the invention will become obvious from the description hereinafter given.

Heretofore it has been common practice to take the fresh air required for the cabinsfrom a separate compressor or from the supercharger x vaillng before and behind the resistance. 1 thermore, with a view to obtain the greatest, qpossible economy, the difierencefin pressure.

by weight a blow-oil? valvewithout materially afl'ecting the amount by weight of air fed into the cabin.-

An independence of altitude of this automatic;

quantitative control will be obtainedby controlling the blow-oft valve by a controlling means operating only on the dlfierencein pressure pre- Furcausing the blowing oif is made only slightly of the driving engine in connection with an addi- 1 tional breathing air compressor, valves having been provided in the induction and delivery higher than the pressure gradient required for V the quantitative control. By means of a profit able utilization of the heat content or energy of pressure oi the overflowing air, the economy pipes, which valves have usually been controlled 1 by the air pressure prevailing in the cabin;

Whilethe desired. air pressure is Yherebymain-j tained in the cabin, the amount and temperature vary, especially-.wlth displacer type compressors,

moredifficult. r 1 1 The present invention-provides for a control of'the'supply of air, permitting the control of pressure, quantity, and temperatureof the raised thus rendering air conditioning of, the cabins each other andpossibly even fully automatair to. be accomplished largely independently of ically in addition in the case of displacer type compressors. q H

" If adisplacer type compressor-for instance,

a Roots bloweris driven bythe :power plant 7 at an almost constantspeed, the weight of air raised by it decreases in proportion to the density of the atmospheric air as the altitude of fiightgincreases, while the volumetric efficiency otthe'compressor remains constant. Therefore the displacer type compressor mustbe so designed as to raise at least the designated amount by weight at the designated altitude. To maintainjan almost constant amount by weight of air which for obvious reasons is desirable for the airing of cabin, the excess air raised at either 'throttled down on the suction side. or blown off on the delivery side. According to the altitudes below the designated height will be present invention, an automatic, quantitative control of the, cabin air is obtained in a manner that, for instance, for a constant amount by weight of fed air, a resistance is placed behind the displacer type compressor, this resistance acting as a throttle and having the effect that,

if the displacer type compressor raises an amount the displacer typ compressor.

' of controlmay be further enhanced. If the utilizationof the overflowing air is not worth while, 1 the surplus air is either blown off into the open air or passed again into the inductionpipes of The latter measure will be preferably adopted if silencers are provided inthe induction and delivery pipes and it is intendedto save such'a silencer in the by-pass'pipes ,or to reduce the loss of pressure in the silencer provided on the suction side.

g If the strictest maintenance of a constant amount by weight of air is insisted-upon, a cone trolling means of special design,. as'described more particularly hereinafter, may be substituted for theresistance;

' The pressure in the cabin is generally con trolled by pressure valves operating independently of altitude and, abovethe nominal altitude,

by blow-oil valves. To make the amount of air as independent of thecontrolling principle of thecabin pressure as possible, a controlling means will be'used whichoperates, within the ranges of pressure occurring, practically independently of the static pressure prevailing at the v outletof the controlling means.

The temperature of the raised air is z deter mined, except by the interior efiiciency of the compressor, by the ratio of pressure between the atmospheric pressure and final pressure of the compressor; Beyond it, the temperature of the raised air may still be elevated by additional throttling of th compressor. .vent the reliability of operation of. the compressor from being impaired by the increases in temperature sometimes required for heating purposes, the present invention provides thatrthe closing of the throttle on the suction side is limof air exceeding that absor'bed by v the resistance, the pressure prevailing between the displacer type compressor and resistance will 1 rise and the surplus air will be blown: off through However, to pre-,

ited by a stop which is adjusted to the permissible working temperatures of the compressor, to a permissible low pressure or to a permissible ratio of pressure of the compressor or the like,

or adjusts itself automatically.

If the amount of breathing air is so selected that at the nominal altitude, say, the minimum heating requirement of the cabin is supplied by the normal work of compression and if at this altitude a certain reserve is still available in respect of the permissible pressure ratio of the compressor, a full-automatic control of air conditioning in the cabin may be achieved by providing a heat I ieeler which remotely controls the throttle of the displacer type compressor to the effect that in the case of deviations of the cabin air temperature from the norminal value first the throttle of the compressor is more or less closed. On reaching the final movement of the throttle closing, the

cases the invention provides that, after the throt tle of the breathing air compressor is fully opened, the further controlling impulses, origi nating either from the operator or heat feeler, switch in a cooling device for the breathing air. Such a cooling device may consist either in a sim- Y ple heat exchanger or special cooling or refrig- V crating equipment.

To explain the invention, an embodiment thereof is shown diagrammatically in the drawings by way of example.

Fig. 1 shows the structure of the whole equipment.

Fig. 2 is a sectional view on the line A-B,

showing the controlling means adapted to keep the amount of air constant.

Rig. 3 is a sectional view on the line -D in Fig. 2. ,l i

Fig. i'is an enlargeclzview showing part of the equipment. 1 I

The breathing air compressor draws the air through the silencer 2 and forces this air through a controlling means 3 adapted to keep the amount of air constant, through the filter or silencer t,

and through the heat exchanger 5 intothe altitude chamber 5 of the aircraft. The air pressure in the chamber 8 is controlled by a pressure valve l and blow-oil valve 8 respectively. Between the breathing air compressor I and controlling means 3 adapted to keep the amount of air constant, a blow-off valve 9 is provided which is controlled through the control box it by the differential pressure of the controlling means 3 adapted "to keep the amount of air constant and blows on the surplus air. The overflowing amount of air is fed again into the induction pipe ii of the comlpressorbetween the silencer 2 and compressor i.

a To control the temperature of the breathing air,

a throttle valve i2 is provided inthe suction pipe ll of the compressor, this throttle valve being keptopen, e. g., by an elastic force shown for example as a spring l3 counteracting a fixed stop i l.

With this embodiment of the invention, the throttie i 2 is operated by a rod and distribution pis asi es? is provided. The controlling rod i5 is provided with slots 39 and to at="the transmitting points and opens, when the throttle valve 52 is closed, a

throttle valve 2t in a heating pipe 26 through which the heat exchanger ti is fed with hot air or hot gasses; under reverse controlling impulses and with the throttle valve l 2 opened, a throttle valve 22 in a cooling air pipe 23 supplying the heat exchanger '5 with cold air is opened.

Figs. 2 and 3 are a diagrammatic view showing a the controlling means 3 adapted to, keep the amount of air constant and the moving'slide 2d of which in the pipe 25 of the flowing through agent acts as a controlling means and, produces a dynamiopressure acting directly on the slide 25, as adjusting force. The slide 2 and its guide case 28 are provided with apertures and which, depending on the particularposition of slide, overlap each other in such a manner that at high dynamic pressures small sectional areas and at low dynamic pressures large sectional areas are exposed for the passage of air. The return movement of the slide 24 is effected by a spring 29, while aspring serves to increase the sensitiveness of control. The space 3! shut ofi by the slide 254 is under equal pressure with the pipe 25 through a bore 38 or other suitable means, to the effect that the controlling means operates only on the dynamic pressure of the flowing through agent and works independently of great or small differences in static pressure between the inlet 25 of the controlling means adapted to keep the amount of air constant and outlet 32.

Finally Fig. 4 shows an example of control of the adjustable stop is for the throttle valve it. Here also the difierence in pressure occurring between the pipe sections 25 and 32 through the controlling device adapted to keep the amount of air constant has been selected as controlling impulse. The stop it follows the movement of a double acting piston 33 which moves, airtlghtly, in a governor case E i under the action of a compression spring 35 towards the throttle valve "i2. On its piston area in space it acts, in addition, the same pressure as in space 32 and on the piston area in space 3'! acts the same pressure as in space 25. From this results at great differences in pressure between 25 and 32 a large opening oi the throttle valve i2 and at small difierences in pressure a slight opening. In a similar way may the adjustable stop it be also controlled by other impulses, for lnstance, by the working temperature of the coin pressor, in order to take account of its maximum permissible temperature.

We claim:

1. In an aircraft a closed cabin com pressor supplying the cabin with fresh air, and means in the delivery pipes of the compressor producinga resistance to the current of air sup plied by the compressor and a difference in pres" sure before and behind s" d means, pipes branching off from the delive before and behind said means and leading to a controlling means adapted to move under difference in pressure and to adjust a valve controlling an out iot in the delivery pipe of thecompressor before the said resistance. it

2. In an aircraft a closed and a som [said resistance.

passage of the resistance.

means in the delivery pipes of the compressor producing a Tesistance to the current of airsupe plied by the compressor. and a difference in pressure before and behind said means and adapted to maintain in said delivery pipes a constant. amount by weight of fed air, pipes branching off from the delivery'pipe before and behind said means andleading to a controlling means adapti ed tomove under the said difference in pressure "and to adjust a valve controlling an outlet in the delivery pipeof the compressor before the 3. Inan aircraft a closed cabin and a compressor supplying the cabin with fresh air, and means in the delivery pipes of the compressor producing a resistance to the current of airsupplied by-the compressor and a diiferencein pressure before and behind said means: and adapted to maintain in said delivery pipes a constant pressure and to adjust a valve controlling an outlet in the delivery pipe of the compressor before the said resistance, said resistance con- ,taining a movable, spring actuated damming means adapted to control the cross :section of 4. In an aircraft a closed cabin sure before and behind said means and adapted tomaintain in said delivery pipes acconstant amount by weight of fed air, pipes branching off I j from the delivery pipe before and behind said ,means and leading to a controlling means adapted to move under the said difference in pressure and to adjust a valve controlling an outlet in the delivery pipe of the compressor before the said resistance, said resistance containing a movable, spring actuated damming means adapted to control the cross section of passage of the 2 0 amount by weight 'of feed air, pipes branching off from the delivery pipe before and behind pressor supplying the cabin with fresh air, and means in the. delivery pipes of the compressor producing a resistance to the current of air supplied bythe compressor and a difference in pressure before and behind said means, pipes branching off from the delivery pipe before and behind said means and leading to a controlling means i adapted to move under the said difference in pressure and to adjust a valve controlling an outlet in the delivery pipe of the compressor before the saidresistance and means adapted to throttle the current of air before the compressor, for controlling the air temperature. In .an aircraft a closedcabin and a com- ,pressorsupplying the cabin with fresh air, and

means in the delivery pipes of the compressor producing'a resistance to the current of air supplied by the compressor and a difference in pressure before and behind said means, pipes branching off from the delivery pipe before and behind said means and leading to a, controlling means adapted to move under the said difference in pressure and to adjust a, valve controlling an outlet in the delivery pipe of the compressor before the said resistance and means adapted to throttle the current of air before the compressor, for controlling the air temperature.

resistance, said damming means being under the action of springs inbothdirections'of move ment. I

5,. In an aircraft a closedicabin anda compressor supplying the cabin with fresh air, and means in the delivery pipes of the compressor producing a resistance to the current of air supplied by the compressor and a difference in 9 pressure before and behind said means, pipes branching off from the delivery pipe before and behind said means and leading to a controlling means adapted to move under the said difierence in pressure and to adjust a valve controlling an outlet in the deliverypipe of the. compressor before the said resistance and means adapted to throttle the current of air before the compressor for controlling the air temperature,

6. In an aircraft a closed cabin and a com.-

8.In an aircraft a closed cabin and a compressor supplying the cabinwith fresh air; and a.

' so and a come pressor supplying the cabin with fresh air, and

means in thedelivery pipes of the compressor producing a resistance to the current of air supplied by the compressor and a difference in presmeans in the deliverypipes of the compressor producing a resistance to the current of air supplied by the compressor and a difference in pressure before and behind said means, pipes branching oil from the delivery pipe before and behind said means and leading to a controlling means adapted tomove under the said difference in pressure and to adjust a valve con-' trolling an outlet in the delivery pipe of the compressor before the said resistance and means adapted to throttle the current of air before the compressor for controlling the air temperature, and valves controlling additional heating and cooling means moved on reaching the final positions of the means adapted to throttle the current of air by a rodprovided with slots at the transmitting points to said valves. 7 s

9. In an aircraft a closed cabin and a comsure before and behind said means, pipes branching' oil from the delivery pipe before and behind said means and leading to a controlling means adapted to move under the said difference in pressure and to, adjust arvalve controlling an outlet in the deliverypipe of the compressor before the said resistance, and adjoining the outlet an outlet pipe in which are interposed heat interchange devices for utilizing the energy of the flowing off air. i r SIEGFRIED GRiJNnRT.

HANS IDE. 

